| madman01 |
| how can i get the focal piont distance on those page magnifires pleaseis there a way to test this |
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| ancorp |
the way I do it, seems pretty accurate is - go outside, and focus the sunlight onto the ground into a small bright dot. Than measure the distance from the dot to the center of the lens.
You can burn stuff with that dot. I tried frying tissue paper, dry leafs and bugs with my big triplet lens. |
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| ace3000_1 |
The safe way to do it is over a table with a room light on, focus the light bulb onto the table, when focused, measure the distance and thats your estimated focal length.
Trev:) |
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| madman01 |
hi guys thanks for your suggestions at this time all i can use are the page mag, for now . i purchased 2 at staples
now what i did is shined a flash light at 15 feet and placed the fressnel until the light was focused on the wall the focused image was at 14 inches
i also did this at 8 feet and got a focused image at 16 inches the closer with the light the farther i needed to focus which still leaves me stumped my projector will probably be 15 to 16 feet away from my screen will this come into play
now for u excellent builders of awsome projectors i need some advice i now have all the major components i need to start constructing my own projector my parts are a 7 inch lcd a triplet from 3m 342 mm,
2 fresnell a 175 watt mh and ballast also a 4 x6 mirror and some plate glass
ive done weeks of research but having suggestions would make my mind at ease on some good ideas on design spacing of fresnells angd objectives etc i dont need to be spoon fed but there r so many diferrent designs out there i cant decide where t start
ok guys i figured out that the focal piont is 14 inches isnt that to much |
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| madman01 |
| quick ? ami even able to use 2 fresnell with same fl im not sure |
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